Name
skyplot -- create simlulated sky spectrum and corresponding line list
Usage
skyplot inlines outlines outimage
Parameters
- inlines = "wmkonspec$lowd_ir_ohlines.dat"
- File listing sky emission features (units of
Ångstroms) and intensities (in arbitrary units).
The default input list is a set of OH sky lines from about 0.8
to 2.3 µm which is suitable for most low-dispersions spectra
taken with NIRSPEC.
- outlines
- Output list of sky emission lines. If none is specified, no
list is produced.
- outimage
- Name of image in which to create simulated night sky
spectrum. If none is specified, no image is produced.
- wavelength = 10000.
- Central wavelength [Angstroms] for the wavelength interval
over which to produce the simulated spectrum and line list.
- dispersion = 2.077
- Dispersion [Angstroms/px] of the resulting spectrum. The
default was appropriate for a test observation, and should be
changed to suit your data.
- fwhm = 5.
- Width of sky lines [px]. This controls the FWHM of the
emission lines in the simulated spectrum. For purposes of
comparing the simulated spectrum to the lines in your data it
is best to input the FWHM of skylines in your sky spectra.
- ncols = 1024
- Number of pixels in spectrum. Generally this should be the
same as the number of pixels in your NIRSPEC data.
- identify = yes
- Determine whether or not to label the emission lines in
the resultant spectrum with their wavelengths.
- nlines = 50
- Number of lines to identify. The nlines strongest
emission lines in the spectrum will be labeled.
- graphics = "stdgraph"
- Graphics outimage device for plot of night sky emission
lines.
Description
Given a list of sky emission features and their relative
intensities, this task will generate a spectrum of these lines
over the specified wavelength interval. Optionally, the task will
create an image and generate a list of the strongest lines in the
spectrum.
The task will generate a simulated sky spectrum, centered on the
specified central wavelength, based on the input line list
inlines. The spectrum has the number of columns
specified by parameter ncols and the specified
dispersion. A plot of the spectrum is sent to the
graphics device specified by the graphics parameter.
If the identify parameter is set true, then the
nlines strongest features in the spectrum will be
labeled with their wavelengths.
If the outlines parameter is defined, the task will
create a list of the nlines strongest features in the
spectrum and save them to a file. This file can then by used as
input to the
identify
task to obtain a wavelength solution based on the night sky
lines.
If the outimage parameter is defined, the task will
store the simulated sky spectrum in the specified image.
Examples
- Generate a list and a corresponding hardcopy plot of the 50
strongest OH night sky lines between 1.0 and 1.25 µm,
putting the linelist into a file lines1.coo:
skyplot wmkonspec$lowd_ir_ohlines.dat lines1.coo \
wavelength=11250. dispersion=2.44 fwhm=5 ncols=1024 \
ident+ nlines=50 graphics=stdplot
Here is the resulting plot.
Notes
- The default linelist is a modified version of that
published by Rousselot et al., 2000, A&A, 354, 1134. This version of the linelist has been modified
to (a) exclude all lines with intensity less than 10
and (b) combine all P1/P2 pairs of unresolved lines.
See Also
identify
The cl script skyplot.cl
The package wmkonspec